1. Technical Field
The present invention relates to a circuit board for the peripheral circuits of a high-capacity module. More particularly, the present invention relates to a circuit board for the peripheral circuits laminated with a circuit including a power semiconductor element, for example, in high-capacity modules including power modules, such as an inverter used in a hybrid vehicle or an electric vehicle. Furthermore, the present invention relates also to a high-capacity module including a peripheral circuit which uses the circuit board.
2. Description of Related Art
Conventionally, in high-capacity (large electric power) modules including power modules, such as an inverter, a circuit (henceforth, may be also referred to as a “power circuit”) including a power semiconductor element, such as a switching element (for example, IGBT (Insulated Gate Bipolar Transistor), MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) etc.) has been arranged in planar with, for example, a peripheral circuit (henceforth, may be also referred to as a “drive circuit”) which controls such a power semiconductor element, and the area for arranging the wiring (wire) for connecting these circuits has been required. These have been factors which hinder reduction in size and weight of a high-capacity module.
In this specification, a high-capacity module refers to the module handling the voltage of 200V or more, or the large electric power of 10 A or more. As an example of such a high-capacity module, for example, what is called a “power module” etc. can be exemplified.
In addition, concerns that wiring length became long due to the wiring for connecting the various circuits which constitute the high-capacity modules as mentioned above, the loss as the whole module becomes larger, and the surge voltage which generates on switching due to the equivalent inductance of the wire becomes larger have been recognized. Excessive surge voltage has a possibility of damaging, for example, a semiconductor element in a drive circuit etc.
By the way, in recent years, for example, along with the popularization of hybrid vehicles and of electric vehicles etc., further improvement in performance such as reduction in size and weight, reduction in surge (surge control), and higher-efficiency (reduction in a loss), etc. is increasingly demanded.
Then, approaches to laminate the circuit boards for various circuits which constitute high-capacity modules as mentioned above in order to attain reduction in size and weight of the high-capacity modules and to improve the connection configuration between the various circuit boards which constitute the high-capacity modules in order to attain reduction in surge and reduction in a loss have been proposed (refer to Patent documents 1 to 3).
When the various circuit boards which constitute a high-capacity module are laminated, as mentioned above, to attain reduction in size and weight of the module, it is known to connect the terminal(s) of a semiconductor element directly to the surface electrode(s) prepared in the surface of a wiring board instead of the connection (wire bond) with wiring (wire) (for example, refer to Patent document 1).
However, the above-mentioned method had a problem that the alignment of the terminal(s) of a semiconductor element with the surface electrode(s) or leadframe terminal(s) of a wiring board was difficult. When the alignment of the terminal of a semiconductor element and the surface electrode(s) or leadframe terminal(s) of a wiring board is insufficient, a problem that the electrical resistance becomes large in the junction(s) constituted with the terminal(s) of a semiconductor element and the surface electrode(s) or leadframe terminal(s) of a wiring board or a problem that the dielectric strength voltage between adjacent junctions becomes insufficient might occur.
Specifically, when the alignment of the terminal(s) of a semiconductor element and the surface electrode(s) or leadframe terminal(s) of a wiring board is insufficient, the contact area of the terminal(s) of a semiconductor element and the surface electrode(s) or leadframe terminal(s) of a wiring board in the junction(s) becomes smaller. As a result, there is a possibility that the electrical resistance in the junction may become larger and it may become impossible to pass an electric current as large as needed for a high-capacity module. Moreover, misalignment of the terminal(s) of a semiconductor element and the surface electrode(s) or leadframe terminal(s) of a wiring board decreases the gap between adjacent junctions. As a result, in these junctions, it may become impossible to secure the dielectric strength voltage needed for applying an electric current with high current or high voltage.
Namely, when the various circuit boards which constitute a high-capacity module are to be laminated to attain reduction in size and weight of the module, it is very important to accurately align the terminal(s) of a power semiconductor element with the surface electrode(s) or leadframe terminal(s) of a wiring board, in order to avoid the problems that the electrical resistance becomes large in the junction(s) constituted with the terminal(s) of the semiconductor element and the surface electrode(s) or leadframe terminal(s) of the wiring board, or the dielectric strength voltage between adjacent junctions becomes insufficient.
However, in the art, when the various circuit boards which constitute a high-capacity module are to be laminated to attain reduction in size and weight of the module, the effective technology which enables the accurate alignment of the terminal(s) of a power semiconductor element and the surface electrode(s) or leadframe terminal(s) of a wiring board in the junction constituted with the terminal(s) of the power semiconductor element or the surface electrode(s) or leadframe terminal(s) of the wiring board has not yet proposed, and therefore a continuous demand to such a technology has been existing.